OBSERVATIONS ON THE DISTRIBUTION AND ECOLOGY OF SIDA HERMAPHRODITA (1.) RUSBY (MALVACEAE) DAVID M. SPOONER Departmentof Botany, The OhioState University Columbus, OH 43210, U.S.A. ALLISON W. CUSICK Ohio Dept. of Natural Resources,Division of Natural Areas & Preserves Columbus, OH 43224, U.S.A. GEORGE F. HALL Departmentof Agronomy,The Ohio State University Columbus, OH 43210, U.S.A. JERRY M. BASKIN School of Biological Sciences, University of Kentucky Lexington, KY 40506, U.S.A. ABSTRACT Sida hermaphrodita (L.) Rusby (Malvaceae) is a perennial herb of riverine habitats in the northeastern and midwestern United States that presently is under consideration for listing as a federally endangered or threatened species. Although the species is rare in most sections of its range, it is locally common in a limited area along the Kanawha and Ohio rivers in West Virginia and Ohio. In contrast to previous reports, evidence is presented that Sida hermaphrodita is indigenous to the Great Lakes drainage. Its disttibution and abundance is not limited either by soil type or by low seed viability or germination potencial. Gametophytic and sporophytic chromosome numbers are 14 and 28, respectively. Al- though Sida hermaphrodita is not immediately in danger of extinction, its habitat continues to be severely altered by man, and no populations of this species presently are protected from destruction. INTRODUCTION Sida hermaphrodita (1.) Rusby (Malvaceae) (Virginia mallow, River mallow) is a polycarpic perennial herb of open, moist, sunny to partly shad- ed riverine habitats. The species is the only member of Pseudonapaea A. Gray, a section without close affinity to any other section in the genus (Clement 1957; Fryxell 1985). The shoots emerge from the soil in April and early May from buds at the base of the previous year's stems and from the ends of numerous radiating rhizomes. Many large populations possibly SIDA 11(2).215-225.1985 216 I are clonal. Flowering begins in early Augusr and continues until a hard I frost occurs. Seeds are dispersed throughout the winter, and they germinate in early spring. It is not known how old the plants are when they first f flower in their natural habitat, but well-watered plants grown in a trans- plant garden can reproduce the same year the seeds germinate. 1 Although geographically widespread (Fig. 1), Sida hermaphrodita is rare in most parts of its tOtal range. Thomas (1979) studied populations of this species in the PotOmac and Susquehanna drainages. He documented that the species had been extirpated from two-thirds of the sites where it had occurred one hundred years prior to his study. On the basis of these results, Thomas recommended that S. hermaphrodita be considered for federal list- ing as an endangered or threatened species. Thomas 0980) also suggested that the species was declining because of occasional flooding of its habitat, natural plant succession, soil compression in (human) populated areas, and low seed germination. Sida hermaphrodita recently has been assigned to Category 2 status of the U.S. Fish and Wildlife Service (Arnett 1983), indicating that it possibly should be federally listed but that substantial supporting evidence is lack- ing. The present study attempts to determine the geographical distribu- tion ofS. hermaphrodita and to ascertain if either soil type or low seed germi- nation potential and/or viability is responsible for the rarity of the species. A considerable amount of research on Sida hermaphrodita by Russian botanists previously has not been cited in the western literature. The species has been studied since 1930 in the southern Ukraine for its econom- ic potential as a soil stabilizer, fodder crop, honey plant, and fiber plant for the pulp and paper industry (Medvedev 1940; Dmitrashko et al. 1971). Seed anatOmy (Savchencko & Dmitrashko 1973) and seed germination (Dmitrashko 1970, 1972, 1973) have been studied in an attempt to in- crease germination percentage. These latter studies indicate that without pretreatment, 10 to 15% offreshly gathered seeds germinate. After 6 to 8 months of stOrage in a laboratory, germination percentage was 60%, but after 13 years stOrage it was less than 10%. Germination percentages have been increased to various degrees by different treatments, including scarifi- cation, soaking in hot water, sulfuric acid, and irradiation with cobalt-60. Spooner wrote Dmitrashko for further details of this research and requested seeds to compare germination results with those reported in this paper. However, Dmitrashko is now retired, and all research on S. hermaphrodita at his institution has been discontinued (in litt. 1982, V. Koval, Dean of BioI. Sci., Odessa State Univ.). 217 MATERIALS AND METHODS Field work was planned using locational data from the following sources: specimens cited in Clement (1957), Iltis (1963), Cusick & Silber- horn (1977), Broome et al. (1979), Thomas (1979), Wiegman (1979), Cranfill & Medley (1981); herbarium specimens from the institutions cited in the acknowledgements; and from Ohio field survey records maintained in the data base of the Division of Natural Areas and Preserves, Ohio De- partment of Natural Resources, Columbus, Ohio. Bulk soil samples from selected populations were analyzed in the Ohio Soil Characterization laboratOry of the Agronomy Department, The Ohio State University. Samples were ground to pass a 2 mm sieve, and all analy- ses were performed on the <2.0 mm fraction. Analyses included pH, particle-size distributin (texture), and organic carbon. Values of pH were determined using a suspension 1: 1 v/v soil/distilled water ratio. The pipette method of Kilmer and Alexander (1949), as modified according to Method 3A 1 of the Soil Conservation Service (1972), was used to deter- mine particle-size distribution. Percent organic carbon was determined by the combustion method of Allison et al. (1965) outlined in Method 6A2b of the Soil Conservation Service (1972). Germination/viability tests were conducted during February 1984 on seeds of S. hermaphrodita collected from 10 natural populations in Adams (two populations), Scioto, Lawrence (two populations), Gallia, and Williams counties, Ohio and from Allegany (two populations) and Cecil counties, Maryland in late summer or autumn of 1982. Seeds were scarified (i.e., a hole was cut through the seed coat) and then incubated on moist filter paper in temperature- and light-controlled incubatOrs at alter- nating temperatures of 35° (day)/20°C (night) at a 14 hour daily photoperiod (20 J.LE/m2/sec, 400 - 700nm, of cool white fluorescent light) for 15 days. Three replications of 50 seeds each were used for each popula- tIOn. The meiotic chromosome count was obtained utilizing techniques out- lined in Keil and Stuessy (1975). The mitOtic count was made from root tips of freshly germinated seeds. Root tips were pretreated in 0.05 M colchicine for 6 hr at 25°C, fixed in a 3: 1 v/v solution of absolute ethanol! glacial acetic acid, hydrolyzed in 0.1 N HC 1 for 15 min at 50°C, and then squashed in acetocarmine. Voucher specimens for the chromosome counts are deposited at OS and US. RESULTS AND DISCUSSION The historical geographical distribution of Sida hermaphrodita is shown in Fig. 1. This map is based on the sources cited above plus new records 218 obtained during this study. Significant early collections not included in the publications of Clement (1957), Iltis (1963), and Thomas (1979), as well as a representative selection of recent new collections, are listed in the ap- pendix to this article. The most extensive and vigorous populations of Sida hermaphrodita are located along the Kanawha River from Charleston, West Virginia to its confluence with the Ohio River at Point Pleasant, and then downstream along both sides of the Ohio River to the vicinity of Huntington, West Virginia. Numerous populations of S. hermaphrodita are scattered along this corridor. The majority of plants grow in sunny, moist, disturbed situations along roadsides and railroad rights-of-way. They occasionally grow in the cinders of railroad embankments. Other populations grow in partially-shaded areas at the edges of woods near streams and rivers. All of these sites are located on riverine terraces or floodplains. Sida hermaphrodita is rare and local in all other sections of its range. In the Ohio River Valley widely scattered populations occur as far west as Clermont Co., Ohio and Campbell Co., Kentucky. In West Virginia, the species occurs sporadically along the Kanawha and New rivers from Charleston south to Summers County. Though not common, small but t. vigorous stands of S. hermaphrodita occur in these valleys. Thomas (1979) has documented the historical distribution and continu- ing decline of S. hermaphrodita in the Potomac and Susquehanna drainages in Maryland, Pennsylvania, Virginia, and the District of Columbia. Re- cent field work by Cusick and Spooner has confirmed the rarity of the species in this area. In Tennessee, the species has not been rediscovered since Gattinger's collections of 1883-1885. Iltis (1963) maps one of Gattinger's specimens as an adventive population, though he does not explain his reason for such an opinion. We consider S. hermaphrodita indigenous to that state. Sida hermaphrodita presently is presumed extirpated from Tennessee (in litt, P Somers, Tennessee Heritage Program). The presence of Virginia mallow in Virginia only recently has been substantiated by specimens (Harvill et al. 1981). Apparently it is very rare in that state. More field work is needed to determine the status of S. hermaphrodita in Virginia. The occurrences of Sida hermaphrodita is Massachusetts, New Jersey, and New York are problematical. The few specimens from these states lack hab- itat data, and they may have been collected from adventive populations or cultivated plants. Whether or not the species is indigenous in these states is debatable. Disjunct populations of Sida hermaphrodita are known from a limited 219 Figure 1. Historical geographical disrriburion of Sida hermaphrodita.